The sintered coal produced from the blast sintering process of coal and lead-zinc mixed concentrate is broken by a multi-stage crushing process. After the first two crushing stages, a part of qualified hot sintering block is directly sent to the blast furnace, and most of the remaining qualified sintering block and the material under the screen are broken through the second two crushing stages to produce the return material that meets the requirements of certain particle size. In recent years, in the process of ironmaking, in order to improve the reducibility of blast furnace and prevent particle segregation, and strengthen production, certain requirements are put forward for the particle size of sintered block entering the blast furnace, so the multi-stage crushing process is also adopted. The Oita First sinter Plant, newly built and put into operation in Japan in 1972, requires that the sintered block size into the blast furnace does not exceed 35 mm, and adopts a three-stage crushing process, and the effective sintering area of the sinter machine is 5×80 meters
2. Mineral sizers can control the qualified block size well, so they are used in the second stage crushing.
Modern large-scale refineries require continuous production of sintering systems. The temperature of the sintered block in mineral sizers can reach 650~750°C, and the working conditions are extremely harsh. Because of the high temperature of the sintered block and the abrasive property, the tooth plate of the crusher is very easy to wear, which seriously affects the normal operation of the crusher. Therefore, it is necessary to seek a kind of material with high wear resistance to high temperature sintered block, in order to extend the service life of the crusher tooth plate; On the other hand, it is also necessary to use a detachable tooth plate connection structure to adapt to the tooth plate can be easily loaded and unloaded and replaced. In order to ensure the normal operation of bearings, efforts should also be made to reduce or eliminate the impact of hot materials on bearings. Because the crusher is working with impact and steep vibration, the torque fluctuation is very large, so that the external dynamic load of the tooth roll is significantly increased, so it is necessary to add a link in the system that can effectively attenuate the impact of steep vibration. In the process of sintering production, it is inevitable that foreign matter will enter the crusher. In order to reduce the failure of "roller", it is required that the double mineral sizers have a large "foreign matter passing capacity". And to prevent the "roller" failure caused by strong power overload caused by the danger. The hot sintering block large double mineral sizers designed by us for Refinery have solved the above problems successfully, and have achieved good results after many years of operation practice in the plant.
The main measure to improve the wear resistance of the tooth plate is to increase the hardness of the tooth plate. Therefore, a material that still has a certain "red hardness" under working conditions of 650~ 700°C is needed. High manganese austenitic steel withstands impact and high pressure forces as a step to improve its "red hardness". Chromium manganese nitrogen austenitic steel is a high temperature anti-oxidation steel, after solid solution treatment has a high temperature mechanical properties, but under the action of high temperature for a long time, due to the "second phase" precipitation and thermal embrittlement, especially in the range of 800~ 900°C is the most intense. mineral sizers operate at 650 to 700° C. We also control the content of chromium and silicon in the material as a lower limit in order to expect it to have a tendency to age hard and brittle while maintaining the appropriate toughness. Make full use of the aging brittleness of the tooth plate material under the working conditions of the tooth roll to improve the wear resistance of the thermal material, so we choose two types of materials, whose chemical composition is shown in Table 2. After two years of use in production, the effect is good, the average wear speed of the crushing plate teeth does not exceed 1 (mm/month). The tooth roll consists of an eight-sided roll body and a removable tooth plate (2A). · The crushing tooth plate and the roll body are connected by bolts. The bolts and nuts are made of low-carbon chrome-molybdenum pearlite steel to prevent the connection from loosening due to stress relaxation. To compensate for thermal deformation, a dish spring is added to the bolted connection.
Under certain conditions, it will quickly produce work hardening, which is a high anti-wear material. However, after this material is toughened by water, and then reheated to 550~750°C, the carbide dissolved in austenite is precipitated again, and the toughness and plasticity of the steel are sharply reduced, resulting in hard and brittle phenomenon. Since chromium is a strong carbide forming element, adding appropriate amount of chromium to high manganese steel is expected to eliminate the influence of high temperature conditions on the reliability of bearing operation, and the main shaft and bearing seat are forced to cool by water at the same time. The hollow shaft is equipped with two spray guns, one of which is fixed and the other moves with the moving roller. Mineral sizers have a central through hole in the main shaft, which has a favorable effect on the tempering process.